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Proceedings Paper

Impact of slanted absorber side wall on printability in EUV lithography
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Paper Abstract

In EUV lithography, when off-axis incident light illuminates an absorber pattern on a reflective multilayer substrate, the side wall of the pattern facing the illumination reflects and absorbs the light, and the side wall on the opposite side casts a shadow. These effects reduce the energy used to create a printed image on a wafer, thereby lowering the image contrast. In addition, when an absorber pattern has a vertical taper, the taper complicates the reflection, absorption and shadowing characteristics. This paper reports on an investigation of how a vertically tapered absorber pattern influences those characteristics and printability based on an analysis of diffracted rays. The printability results revealed that the taper introduces a new error source, namely, the CD (critical dimension) difference on wafer between parallel and perpendicular incidences. The allowable CD difference was found to determine the latitude in the side-wall angle. Moreover, it was found that a thinner absorber increases both the allowable CD difference and the latitude in the side-wall angle at the same time.

Paper Details

Date Published: 8 November 2005
PDF: 10 pages
Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 59923V (8 November 2005); doi: 10.1117/12.632419
Show Author Affiliations
Minoru Sugawara, Association of Super-Advanced Electronic Technologies (Japan)
Iwao Nishiyama, Association of Super-Advanced Electronic Technologies (Japan)

Published in SPIE Proceedings Vol. 5992:
25th Annual BACUS Symposium on Photomask Technology
J. Tracy Weed; Patrick M. Martin, Editor(s)

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